Experimental Research On Oxygen Decoupling Properties Of Cu/Mn Combined Oxygen Carrier Based On Chemical Looping

Oxygen is rich in nature,widely used in energy,metallurgy,chemistry,defense,health care and other industries.Chemical looping air separation technology is a new type of oxygen production technology,with low energy consumption,low cost,simple operation,high purity oxygen,etc.,and get a high degree of concern in the field of oxygen production.The research of oxygen carrier is the basis and key of chemical looping technology industrial application.In terms of reaction performance,the oxygen carrier suitable for CLAS technology should ensure a faster rate and a larger amount of oxygen during the oxidation and reduction reaction.At the same time,it also should have good cycle stability.The study found combined metal oxygen carrier can effectively improve the limitations of single metal oxygen carrier itself.Therefore,in this paper,taking Cu/Mn combined metal oxide oxygen as the object of study and using the experimental method to study the reduction and oxidation performance.The main contents and conclusions of this paper are as follows(1)The effect of preparation parameters on the reduction and oxidation performance of combined oxygen carrier was studied by using a thermogravimetric analyzer and the obtained results were as followed:The amount of the oxygen release and the stability of oxygen carrier prepared by the mechanical mixing method were significantly higher than that prepared by the sol-gel method.With the increased of calcination temperature,the oxygen release time reduced and the reaction rate accelerated.When the calcination temperature reached 950?,the oxidation rate of the oxygen carrier decreased.For the oxygen carrier with calcination time was 6h and 10h respectively.The difference of oxidation and reduction performance was not obvious,and the redox reaction can be completed in a short time.It also showed that the oxygen carrier has good high temperature stability in the preparation process.Above all,in this paper,the optimal preparation method is mechanical mixing method.The optimal calcination temperature is 950?.The optimal calcination time is 6h.(2)Based on the method of phase analysis,the physical properties of the oxygen carrier were characterized.It was found that the active components did not react with the inert during the preparation process of the combined oxygen carrier.There was no significant difference in the composition of the oxygen carrier prepared by the different preparation parameters.The phase of fresh oxygen carrier was(Cu,Mn)3O4 and ZrO2,The phase of reduced oxygen carrier was CuMnO2 and ZrO2;The grain size range of oxygen carrier prepared by the mechanical mixing method was 16?18nm.The grain size range of oxygen carrier prepared by the sol-gel method was 14?15nm.(3)The oxygen carrier with the optimal preparation parameters was analyzed through the thermal state experimental and the results showed as follows:Compared with Cu-based oxygen carrier,the combined oxygen carrier can release oxygen at 650?850?,decreasing the release temperature range of Cu-based oxygen carrier.What is more,With the increased of the inlet flow of the reactor,the reaction time reduced and the reaction rate increased.In the reduction reaction process,the higher reaction temperature and the lower oxygen concentration of the inlet lead to the faster reduction rate of the oxygen carrier;In the oxidation reaction process,the lower reaction temperature and the higher oxygen concentration of the inlet lead to the faster oxidation rate of the oxygen carrier;With the increased of the particles diameter,the redox reaction time decreased and the redox reaction rate increased.(4)Based on the experimental data of thermal state,the isothermal kinetics analysis of oxygen carrier was carried out and the results showed as follows:In the reduction process,the reaction model of combined oxygen carrier was the shrinkage kernel model R2(spherical symmetry),and the reaction order n=2;In the oxidation process,the reaction model of the combined oxygen carrier was the random nucleation model A2,and the reaction order n=2.The order of reduction reaction activation energy of two kind of oxygen carriers was Cu/Mn/Zr 2:1:1<Cu/Mn/Zr 1.5:1:1,indicating that Cu/Mn/Zr 2:1:1 had a better reduction performance.When the temperature ranges from 650? to 750?,the oxidation reaction activation energies of the two oxygen carriers were negative.This is to say the temperature rise hindered the oxidation reaction of oxygen carrier.